[Treatment of post-herpes zoster pain with tramadol. Results of an open pilot study versus clomipramine with or without levomepromazine]

Abstract

To date, no universally applicable recommendations are available for the treatment of patients with postherpetic neuralgia. A mixture of clinical anecdotes, experimental findings and observations from clinical trials form the basis of the medical arsenal for this condition. Tricyclic antidepressants are commonly used, and clinical experience and several investigations have documented their effectiveness. Today, single entity antidepressants, which can be combined with neuroleptics to increase analgesia, are generally recommended for the treatment of postherpetic neuralgia. Some authors also recommend the additional administration of an opioid if analgesia is inadequate. Just over a decade ago, opioids were considered ineffective for the treatment of neuropathic pain; however, more recent investigations relating to the use of opioids, primarily in the treatment of nontumour-related chronic pain, have led to a revision of their use in neuropathic pain. Nevertheless, the use of opioid therapy for neurogenic pain remains controversial. Tramadol is a synthetic, centrally acting analgesic with both opioid and nonopioid analgesic activity. The nonopioid component is related to the inhibition of noradrenaline (norepinephrine) reuptake and stimulation of serotonin (5-hydroxytryptamine; 5-HT) release at the spinal level. In this regard, there are parallels with antidepressants, which are believed to potentiate the effect of biogenic amines in endogenous pain-relieving systems. There is evidence that, in tramadol, both mechanisms act synergistically with respect to analgesia. The aim of this pilot study was to investigate, for the first time, the analgesic efficacy and tolerability of tramadol, compared with the antidepressant clomipramine, in the treatment of postherpetic neuralgia. If necessary, clomipramine was used in combination with the neuroleptic levomepromazine. The study allowed individualised dosages at predetermined intervals up to a maximum daily dose of tramadol 600mg and clomipramine 100mg, or clomipramine 100mg with or without levomepromazine 100mg. 21 (60%) of 35 randomised patients (> or = 65 years) received the study medication over the 6-week period [tramadol n = 10; clomipramine with or without levomepromazine) n = 11]. After 3 weeks' treatment the dosage in both groups remained almost constant for the rest of the 6-week treatment phase (mean daily dose: tramadol 250 to 290mg; clomipramine 59.1 to 63.6mg). Only 3 patients required the combination of clomipramine and levomepromazine. At the outset, both groups recorded an average pain level of 'moderate' to 'very severe'. In correlation with increasing the study medication, this had decreased to 'slight' by the end of the treatment, when 9 of 10 patients in the tramadol group and of 6 of 11 patients in the clomipramine group retrospectively rated their analgesia as excellent, good or satisfactory. The psychological/physical condition of the patients did not change significantly during tramadol treatment. Sensitivity and depression parameters decreased in the clomipramine group. The incidence of adverse events for all patients was similar in both groups (tramadol 76.5%; clomipramine with or without levomepromazine 83.3%). In conclusion, tramadol would appear to be an interesting therapeutic alternative for pain relief in postherpetic neuralgia, particularly in patients who are not depressed. In clinical practice, tramadol and clomipramine can best be used differentially. For example, tramadol could be the drug of first choice in patients with obvious cardiovascular disease (not an uncommon problem in the > or = 65 year age group) in whom antidepressants are contraindicated, and similarly in patients in whom an antidepressant effect is not required. (ABSTRACT TRUNCATED)